In the preparation of a road bed, surveyor stakes are driven in the ground at spaced intervals and a line is strung between for indicating the course of the road and for indicating how much earth needs to be removed or filled at a particular location. The line guide technique may also be employed by a curb-laying machine to aid in steering the machine by providing height and azimuth direction along the roadside. It will be appreciated that the accuracy of the line guide is an important factor in roadway construction.